Detecting disease with a smartphone accessory
Engineers have created a new optical sensor that plugs in to a smartphone and, using disposable microfluidic chips, allows for inexpensive in-the-field diagnosis of Kaposi’s sarcoma, a cancer linked to AIDS.
June 4, 2013 — As antiretroviral drugs that treat HIV have become more commonplace, the incidence of Kaposi’s sarcoma, a type of cancer linked to AIDS, has decreased in the United States. The disease, however, remains prevalent in sub-Saharan Africa, where poor access to medical care and lab tests only compound the problem. Now, Cornell University engineers have created a new smartphone-based system, consisting of a plug-in optical accessory and disposable microfluidic chips, for in-the-field detection of the herpes virus that causes Kaposi’s. “The accessory provides an ultraportable way to determine whether or not viral DNA is present in a sample,” says mechanical engineer David Erickson, who developed the technique along with his graduate student, biomedical engineer Matthew Mancuso. The technique could also be adapted for use in detecting a range of other conditions, from E. coli infections to hepatitis.Share This:Mancuso will describe the work at the Conference on Lasers and Electro Optics (CLEO: 2013), taking place June 9-14 in San Jose, Calif.Unlike other methods that use smartphones for diagnostic testing, this new system is chemically based and does not use the phone’s built-in camera. Instead, gold nanoparticles are combined (or “conjugated”) with short DNA snippets that bind to Kaposi’s DNA sequences, and a solution with the combined particles is added to a microfluidic chip. In the presence of viral DNA, the particles clump together, which affects the transmission of light through the solution. This causes a color change that can be measured with an optical sensor connected to a smartphone via a micro-USB port. When little or no Kaposi’s virus DNA is present, the nanoparticle solution is a bright red; at higher concentrations, the solution turns a duller purple, providing a quick method to quantify the amount of Kaposi’s DNA.The main advantage of the system compared to previous Kaposi’s detection methods is that users can diagnose the condition with little training. …
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